Method of manufacturing a merged MR head

ABSTRACT

A merged MR head is formed by sequentially stacking a lower shield, a lower shield gap, a magnetoresistive (MR) element, an upper shield gap, a lower magnetic pole/upper shield, a recording gap layer, a coil, a coil insulating layer, and an upper magnetic pole on a side surface of a trailing edge of a floating slider having an air bearing surface. This merged MR head includes a pedestal which is formed on a portion on the lower magnetic pole/upper shield, including the air bearing surface, to have a width larger than that of the upper magnetic pole. The upper magnetic pole is stacked on the pedestal through the recording gap layer. A sidewall of the pedestal in the vicinity of the air bearing surface has a notch which is obtained by forming a plane where a sidewall of the upper magnetic pole is present. A method of manufacturing this merged MR head is also disclosed.

BACKGROUND OF THE INVENTION

The present invention relates to a merged MR (magnetoresistive) headhaving aligned magnetic pole tips, and a method of manufacturing thesame.

In a magnetic disk drive, data is read and written by using a magneticdisk medium serving as a storage medium, and a magnetic head having aelectromagnetic transducing element mounted on a floating sliderfloating and supported by the air bearing effect caused by high-speedrotation of the magnetic disk medium.

Recent demands for an internal storage unit or external storage unit ofa personal computer and the like increase remarkably, and downsizing, ahigher operation speed, and a higher recording density are stronglydemanded in a magnetic disk drive.

For this reason, improvements for high performance have been made in themagnetic head serving as the major portion of the magnetic disk drive,the magnetic disk medium, positioning servo, signal processing, and thelike. In particular, whereas the magnetic head conventionally performswrite (recording) and read (play) with one electromagnetic transducingelement, recently, use of a so-called write/read separation type mergedMR head is becoming the main stream. The merged MR head uses aconventional inductive element for data write, and an MR element, theoutput of which does not depend on the speed relative to the magneticdisk medium and which utilizes the magnetoresistive effect, for dataread. These two elements are integrated and mounted on one floatingslider.

This merged MR head is manufactured by utilizing photolithographytechnique, and micropatterning technique similar to a semiconductormanufacturing process. For example, Japanese Patent Laid-Open No.7-262519 (U.S. Pat. No. 5,438,747) discloses a merged MR head and atechnique concerning a method of manufacturing the same.

FIGS. 5A to 5C show an example of a method of manufacturing aconventional merged MR head.

In order to decrease the side fringe magnetic field generated duringrecording, the conventional merged MR head has a recording gap layerhaving the same width as that of an upper magnetic pole and a sidewallaligned with the same plane where the side surface of the upper magneticpole is present, and the pedestal of a lower magnetic pole/upper shield.

In the method of manufacturing a conventional merged MR head, therecording gap layer and the pedestal of the lower magnetic pole/uppershield are formed to have the same width as that of the upper magneticpole. For this purpose, the recording gap layer is defined to have thesame width as that of the upper magnetic pole by using ion milling andchemical etching. Subsequently, in accordance with ion milling, thepedestal of the lower magnetic pole/upper shield, having the same widthas that of the upper magnetic pole and a side surface aligned with thesame vertical plane where the side surface of the upper magnetic pole ispresent, is formed on the lower magnetic pole/upper shield by using theupper magnetic pole as the mask.

FIGS. 5A to 5C show the manufacturing method which uses ion milling whendefining the recording gap layer to have the same width as that of theupper magnetic pole. A recording gap layer 23 is deposited on a lowermagnetic pole/upper shield 22, and thereafter an upper magnetic pole 24is formed on the recording gap layer 23 by electroplating usingphotoresist frame. A portion of the resultant structure other than thevicinity of the upper magnetic pole 24 is covered with a photoresist 26,and the recording gap layer 23 is defined by ion milling to have thesame width as that of the upper magnetic pole 24.

Since the ion beam etching rate of the recording gap layer 23 is lowerthan the ion beam etching rate of the upper magnetic pole 24, whendefining the recording gap layer 23 to have the same width as that ofthe upper magnetic pole 24, the thickness (height) of the upper magneticpole 24 decreases largely. More specifically, FIG. 5A shows a statebefore the recording gap layer 23 is etched by ion milling, and FIG. 5Bshows a state after the recording gap layer 23 is defined by ion millingby using the upper magnetic pole 24 as the mask (the broken line in FIG.5B shows a portion to be etched by ion milling). In FIG. 5B, thethickness of the upper magnetic pole 24 is apparently smaller than thatin FIG. 5A.

Subsequently, as shown in FIG. 5C, a pedestal 21 for the lower magneticpole/upper shield 22 is formed on the lower magnetic pole/upper shield22 in accordance with ion milling by using the upper magnetic pole 24 asthe mask. The pedestal 21 has the same width as that of the uppermagnetic pole 24 and is aligned with the same vertical plane where asidewall or surface 24s of the upper magnetic pole 24 is present. Inthis case, the thickness of the upper magnetic pole 24 furtherdecreases.

In other words, FIG. 5B shows a state before the pedestal 21, alignedwith the same vertical plane where the side surface of the uppermagnetic pole 24 is present, is defined on the lower magnetic pole/uppershield 22 in accordance with ion milling by using the upper magneticpole 24 as the mask. FIG. 5C shows a state after the pedestal 21 isdefined on the lower magnetic pole/upper shield 22 by using the uppermagnetic pole 24 as the mask.

In FIG. 5C, the sidewall 24s of the upper magnetic pole 24, a sidewall23s of the recording gap layer 23, and a sidewall 21s of the pedestal 21are aligned within the same plane 25. Similarly, the respectivesidewalls on the opposite side (the left-hand side in FIG. 5C) arealigned within the same plane.

FIGS. 6A to 6C show another example of a conventional merged MR head anda method of manufacturing the same.

A recording gap layer 33 is formed on a lower magnetic pole/upper shield32, and thereafter an upper magnetic pole 34 is formed on the recordinggap layer 33 by electroplating using photoresist frame. Subsequently,the recording gap layer 33 is defined to have the same width as that ofthe upper magnetic pole 34 by chemical etching.

In this case, since a chemical etching solution that etches not theupper magnetic pole 34 but the recording gap layer 33 can be selected,the thickness (height) of the upper magnetic pole 34 does not decrease.Subsequently, a pedestal 31 for the lower magnetic pole/upper shield 32is formed on the lower magnetic pole/upper shield 32 in accordance withion milling by using the upper magnetic pole 34 as the mask. Thepedestal 31 has the same width as that of the upper magnetic pole 34 andis aligned with the same vertical plane as the side surface of the uppermagnetic pole 34. In this case, the thickness of the upper magnetic pole34 decreases (the broken line in FIG. 6B shows a portion to be etched byion milling).

In the conventional merged MR head manufacturing methods describedabove, the thickness of the upper magnetic pole becomes undesirablysmaller than the thickness necessary to generate a sufficiently strongmagnetic field when the merged MR head records a signal on the magneticrecording medium.

The reason for this is as follows. When forming the recording gap layerand the pedestal of the lower magnetic pole/upper shield by ion millingin order to decrease the side fringe magnetic field, the upper magneticpole serving as the mask during ion milling must be formed thicker inadvance by an amount corresponding to the thickness decreased by ionmilling. For this purpose, the photoresist required for forming theupper magnetic pole by electroplating using photoresist frame must beformed to have a thickness larger than that of the necessary uppermagnetic pole and to have a desired width of the upper magnetic pole.However, as the width of the upper magnetic pole decreases to meet ademand for a higher density, such a photoresist becomes difficult toform.

In the former case, since the ion beam etching rate of the recording gaplayer 23 is lower than the ion beam etching rate of the upper magneticpole 24, when defining the recording gap layer 23 to have the same widthas that of the upper magnetic pole 24, the thickness of the uppermagnetic pole 24 decreases largely. In other words, the thickness of theupper magnetic pole 24 decreases largely in accordance with theprocedure from FIG. 5A to FIG. 5B.

When forming the pedestal 21 for the lower magnetic pole/upper shield 22by ion milling using the upper magnetic pole 24 as the mask, thethickness of the upper magnetic pole 24 further decreases. As a result,the thickness of the upper magnetic pole, which is necessary to generatea sufficiently strong magnetic field when recording a signal on themagnetic recording medium, may not be ensured.

In particular, when the width of the upper magnetic pole 24 becomesequal to or less than 2 μm, the thickness of the upper magnetic pole 24that can be formed by electroplating using photoresist frame is about 5μm at maximum. Therefore, when ion milling is performed for therecording gap layer 23 and the pedestal 21 portion for the lowermagnetic pole/upper shield 22 by using the upper magnetic pole 24 as themask, the thickness of the upper magnetic pole 24 becomes equal to orless than 3 μm, which is smaller than the required thickness, 4 μm.

In the latter case, the sidewall of the recording gap layer and thesidewall for the pedestal of the lower magnetic pole/upper shield cannotbe formed on the same plane where the sidewall of the upper magneticpole is present.

The reason for this is as follows. Assume that in order to avoid theproblems of the former case, the recording gap layer is to be formed bychemical etching to have the same width as that of the upper magneticpole and to have a sidewall within the same vertical plane where thesidewall of the upper magnetic pole is present. In this case, due tovariations in chemical etching rate, it is difficult to stop etching assoon as the sidewall of the recording gap layer becomes located on thesame plane where the sidewall of the upper magnetic pole is present.

More specifically, due to variations in etching rate of the recordinggap layer 33 etched with a chemical etching solution, it is difficult tostop chemical etching as soon as the side surface of the recording gaplayer 33 reaches the same plane 37a or 37b where a side surface or wall34s of the upper magnetic pole 34 is present. As a result, as shown inFIG. 6B, the side surface of the recording gap layer 33 undesirablyextends to the outer side of the same plane 37a where the sidewall 34sof the upper magnetic pole 34 is present, thus forming an etch residue35, or the side surface of the recording gap layer 33 undesirablyretreats backward to the inner side of the same plane 37b where thesidewall 34s of the upper magnetic pole 34 is present, thus causing anover-etching 36.

In the etch residue 35 portion, the over-extending recording gap layer33 forms a mask. As shown in FIG. 6C, a sidewall 31s (on the left inFIG. 6C), on the opposite side, of the pedestal 31 for the lowermagnetic pole/upper shield 32 is formed on a plane 38 on the outer sideof the same plane 37a where the sidewall 34s of the upper magnetic pole34 is present. Accordingly, the side fringe magnetic field is notdecreased.

Furthermore, in a portion of the recording gap layer 33 where theover-etching 36 has occurred, the sidewall 31s of the pedestal 31 forthe lower magnetic pole/upper shield 32 can be formed on the same planes37a and 37b where the sidewall 34s of the upper magnetic pole 34 ispresent. However, the over-etching 36 portion of the recording gap layer33 is not filled even in the later steps but is left as a hole. Aforeign matter may enter through this hole to reach an element portioncovered with a protection film, to corrode the element.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a merged MR head inwhich the upper magnetic pole is formed to have a width equal to or lessthan 2 μm to perform high-density magnetic recording, and a method ofmanufacturing the same.

It is another object of the present invention to provide a merged MRhead in which the sidewall of the upper magnetic pole and the sidewallof the pedestal for the lower magnetic pole/upper shield are aligned onthe same plane, and a method of manufacturing the same.

In order to achieve the above objects, according to the presentinvention, there is provided a merged MR head formed by sequentiallystacking a lower shield, a lower shield gap, a magnetoresistive (MR)element, an upper shield gap, a lower magnetic pole/upper shield, arecording gap layer, a coil, a coil insulating layer, and an uppermagnetic pole on a side surface of a trailing edge of a floating sliderhaving an air bearing surface, wherein the merged MR head comprises apedestal which is formed on a portion on the lower magnetic pole/uppershield, including the air bearing surface, to have a width larger thanthat of the upper magnetic pole, the upper magnetic pole being stackedon the pedestal through the recording gap layer, and a sidewall of thepedestal in the vicinity of the air bearing surface has a notch which isobtained by forming a plane where a sidewall of the upper magnetic poleis present.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1F are views showing the steps in manufacturing a merged MRhead according to the first embodiment of the present invention, inwhich the shape of a magnetic pole tip seen from a side corresponding tothe air bearing surface of a merged MR head element is shown in theorder of manufacturing steps;

FIGS. 2A to 2E are views showing the steps in manufacturing a merged MRhead according to the second embodiment of the present invention, inwhich the shape of a magnetic pole tip seen from a side corresponding tothe air bearing surface of the merged MR head element is shown in theorder of manufacturing steps;

FIGS. 3A to 3E are views showing the steps in manufacturing a merged MRhead according to the third embodiment of the present invention, inwhich the shape of a magnetic pole tip seen from a side corresponding tothe air bearing surface of the merged MR head element is shown in theorder of manufacturing steps;

FIGS. 4A and 4B are views showing a method of manufacturing a merged MRhead according to the fourth embodiment of the present invention;

FIGS. 5A to 5C are views showing the steps in an example of a method ofmanufacturing a conventional merged MR head; and

FIGS. 6A to 6C are views showing the steps in another example of amethod of manufacturing a conventional merged MR head.

DESCRIPTION OF THE EMBODIMENTS

The present invention will be described in detail with reference to theaccompanying drawings.

FIGS. 1A to 1F show the steps in a method of manufacturing a merged MRhead according to an embodiment of the present invention. In FIGS. 1A to1E, the shape of a portion above a lower magnetic pole/upper shield 2 isshown in the order of manufacturing steps. FIG. 1F shows the shape of amagnetic pole tip seen from a surface corresponding to the air bearingsurface of a completed merged MR head.

To obtain this merged MR head, as shown in FIG. 1F, a lower shield 7 isformed, an MR element 6 is formed, and thereafter the lower magneticpole/upper shield (to be referred to as the upper shield hereinafter) 2is formed. After formation of the upper shield 2, a pedestal for thelower magnetic pole/upper shield (to be referred to as a pedestalhereinafter) 1, having a width 1w slightly larger than the width (5w) ofan upper magnetic pole 5 and a height 1h equal to or larger than therecording gap layer thickness (3t), is selectively formed on the uppershield 2 (FIG. 1A).

A recording gap layer 3 having a thickness 3t is formed on the uppershield 2 and pedestal 1. Since the upper shield 2 has the pedestal 1,the thickness of the recording gap layer 3 on the corner of the pedestal1, i.e., the thickness of a corner 4, becomes smaller than the recordinggap layer thickness 3t (FIG. 1B).

A lower insulating layer, a coil, and an upper insulating layer (lattertwo are not shown) that constitute the merged MR head are formed. Inthis formation, the thickness of the recording gap layer corner 4 isfurther decreased. Subsequently, the upper magnetic pole 5 having athickness 5t and the width 5w is formed on the recording gap layer 3 inthe pedestal 1 region by electroplating using photoresist frame (FIG.1C).

By using the upper magnetic pole 5 as the mask, the recording gap layer3 and the pedestal 1 are notched (removed) by ion milling to have thesame width as the width 5w of the upper magnetic pole 5 (FIG. 1D). InFIG. 1D, the broken line indicates a portion to be etched by ionmilling. As a result, a sidewall 5s of the upper magnetic pole 5, asidewall 3s of the recording gap layer 3, and a sidewall 1s of thepedestal 1 are formed within the same plane 10 (FIG. 1E).

The structure of a merged MR head having a floating slider with an airbearing surface, and a coil and a coil insulating layer stacked on thefloating slider is described in Japanese Patent Laid-Open No. 7-262519(U.S. Pat. No. 5,438,747), and a description thereof will be omittedaccordingly. The structure of the merged MR head described in thisreference is incorporated in this embodiment.

The steps of FIGS. 1A to 1F described above will be individuallydescribed in detail.

Referring to FIG. 1A, the width 1w of the pedestal 1 is formed to beslightly larger than the width 5w of the upper magnetic pole 5 so that,even if the position of the photoresist frame used when forming theupper magnetic pole 5 by electroplating using photoresist frame mayslightly vary, the end of the photoresist frame is formed on thepedestal 1. When considering these variations, the width 1w of thepedestal 1 is preferably larger than the width 5w of the upper magneticpole 5 by 0.1 μm to 2.0 μm, and is particularly most preferably largerby 1.0 μm. With this size, the corner 4 is exposed beside the lowerportion of the upper magnetic pole 5.

The height 1h of the pedestal 1 is preferably larger than the recordinggap layer thickness 3t. For example, when the recording gap layerthickness 3t falls within the range of 0.1 μm to 0.5 μm, the height 1hof the pedestal 1 preferably falls within the range of 0.1 μm to 2 μm.In particular, the height 1h of the pedestal 1 is preferably equal to orlarger than twice the recording gap layer thickness 3t. For example,when the recording gap layer thickness 3t is 0.3 μm to 0.4 μm. theheight 1h of the pedestal 1 is preferably equal to or larger than 1.0μm.

This is because it facilitates formation of a notched portion height 8of the pedestal 1, having the sidewall 1s aligned within the same planewhere the sidewall 5s of the upper magnetic pole 5 is present, to beequal to or larger than twice the recording gap layer thickness 3t.

Referring to FIG. 1B, since a step formed by the pedestal 1 is presenton the upper shield 2, a thickness 4t of the recording gap layer corner4 on the corner of the pedestal 1 becomes smaller than the recording gaplayer thickness 3t on the pedestal 1. For example, when the recordinggap layer thickness 3t falls within the range of 0.3 μm to 0.4 μm, thethickness 4t of the recording gap layer corner 4 is decreased to 0.2 μmto 0.1 μm.

Referring to FIG. 1C, after the upper magnetic pole 5 is formed byelectroplating using photoresist frame, the photoresist that has servedas the frame is removed. When the width 5w of the upper magnetic pole 5is equal to or smaller than 2 μm, the thickness 5t of the upper magneticpole 5 can be formed to as small as 5 μm at maximum. This is becausewhen the upper magnetic pole 5 is to be formed by electroplating usingphotoresist frame, the thickness of the photoresist, that serves as theframe when forming the width 5w of the upper magnetic pole 5 to be equalto or smaller than 2 μm, can be formed to as small as 5 μm at maximum.

In other words, if the thickness of the thinnest portion of thephotoresist that serves as the frame is set to be equal to or largerthan 5 μm, the thickness of a portion of the photoresist correspondingto a 5w-width portion of the upper magnetic pole 5 becomes equal to orlarger than 10 μm, and the width 5w of the upper magnetic pole 5 cannotbe formed to be equal to or smaller than 2 μm accordingly.

In the steps of forming the lower insulating layer, the coil, and theupper insulating layer, the thickness 4t of the recording gap layercorner 4 is decreased to about 1/5 to 1/6 the recording gap layerthickness 3t due to ion milling which is practiced when forming thecoil. For example, when the recording gap layer thickness 3t is 0.3 μmto 0.4 μm, the thickness 4t of the recording gap layer corner 4 isdecreased to 0.08 μm to 0.05 μm.

This is due to the following reason. When performing ion milling to formthe coil, in order to remove the film between the coils, an ion beam ismade incident in a direction perpendicular, or close to perpendicular,to the upper shield 2. Because of the presence of the pedestal 1, thesurface of the recording gap layer corner 4 is obliquely inclined, asshown in FIG. 1B, and the ion beam comes incident on the recording gaplayer corner 4 obliquely.

When the recording gap layer 3 is made of, e.g., aluminum oxide, the ionmilling rate for aluminum oxide is larger in oblique incidence of theion beam than in perpendicular incidence. As a result, the recording gaplayer corner 4 is etched in a larger amount than the recording gap layer3 on the upper shield 2.

Since the width 1w of the pedestal 1 is slightly larger than the width5w of the upper magnetic pole 5, the recording gap layer corner 4 isexposed under the right and left sidewalls of the upper magnetic pole 5.

Referring to FIGS. 1D and 1E, the recording gap layer 3 and the pedestal1 are defined to have the same width as that of the upper magnetic pole5 by ion milling using the upper magnetic pole 5 as the mask. In thiscase, of the recording gap layer 3 which is etched by ion milling, aportion corresponding to the corner of the pedestal 1 formed to have thewidth 1w slightly larger than the width 5w of the upper magnetic pole 5slightly extends horizontally from the upper magnetic pole 5, so thatthe recording gap layer corner 4 is exposed laterally at the lowerportion of the sidewall 5s of the upper magnetic pole 5. Accordingly,the width of the recording gap layer 3 can be defined to the thickness5t of the upper magnetic pole 5 by only etching the recording gap layercorner 4 which has a thickness 1/5 to 1/6 the recording gap layerthickness 3t on the pedestal 1.

In particular, when the width 1w of the pedestal 1 is formed to belarger than the width 5w of the upper magnetic pole 5 by 0.1 μm to 2.0μm, the recording gap layer corner 4 can be exposed laterally at thelower portion of the sidewall 5s of the upper magnetic pole 5. When thewidth 1w of the pedestal 1 is formed to be larger than the width 5w ofthe upper magnetic pole 5 by 1.0 μm, the recording gap layer corner 4can be exposed laterally at the lower portion of the sidewall 5s of theupper magnetic pole 5 most reliably.

More specifically, before deposition of the recording gap layer 3, thepedestal 1 is formed to have a width slightly larger than the width 5wof the upper magnetic pole 5, so that the recording gap layer corner 4having a thickness 1/5 to 1/6 the recording gap layer thickness 3t onthe pedestal 1 can be exposed laterally at the lower portion of thesidewall 5s of the upper magnetic pole 5. Accordingly, the ion millingtime required for defining the recording gap layer 3 to have the width5w of the upper magnetic pole 5 by ion milling using the upper magneticpole 5 as the mask can be decreased to 1/5 to 1/6 the conventionallyrequired time. As a result, the amount of decrease in thickness 5t ofthe upper magnetic pole 5, obtained when defining the recording gaplayer 3 to have the width 5w of the upper magnetic pole 5 by ionmilling, can be decreased to 1/5 to 1/6 the conventionally requiredamount.

Referring to FIG. 1E, after the recording gap layer 3 is defined to havethe width 5w of the upper magnetic pole 5 by ion milling, the pedestal 1is sequentially defined to have the width 5w of the upper magnetic pole5 by ion milling using the upper magnetic pole 5 as the mask.

In this manner, when the recording gap layer 3 and the pedestal 1 aredefined in accordance with ion milling by using the upper magnetic pole5 as the mask, the sidewall 5s of the upper magnetic pole 5, thesidewall 3s of the recording gap layer 3, and the sidewall 1s of thenotched portion of the pedestal 1 can be formed within the same plane10.

When defining the pedestal 1 and recording gap layer 3 to have the width5w of the upper magnetic pole 5 by using the upper magnetic pole 5 asthe mask, the height 8 of the notched portion of the pedestal 1 ispreferably formed to be equal to or larger than twice the recording gaplayer thickness 3t. This is because it can decrease widening of thefringe magnetic field during recording.

The amount of decrease in thickness of the upper magnetic pole 5,obtained when defining the recording gap layer 3 and the pedestal 1 byion milling using the upper magnetic pole 5 as the mask, is the sum ofthe amount of decrease obtained when removing the recording gap layer 3and the amount of decrease obtained when notching the pedestal 1 for thelower magnetic pole/upper shield 2 to have the same width as that of theupper magnetic pole 5. When the recording gap layer thickness 3t is 0.3μm to 0.4 μm, the amount of decrease in thickness of the upper magneticpole 5, obtained when removing the recording gap layer 3, is about 0.1μm to 0.2 μm when calculated on the basis of the thickness of theremaining recording gap layer 3 (1/5 to 1/6 the initial value) and therate ratio (about twice) in ion milling of the material of the recordinggap layer to the material of the magnetic pole.

The amount of decrease in thickness of the upper magnetic pole 5,obtained when notching the pedestal 1, is 0.6 μm to 0.8 μm when thenotched portion height 8 is set to equal or larger than twice that ofthe recording gap layer 3. Accordingly, when the thickness of theinitial upper magnetic pole 5 is 5 μm, the thickness of the uppermagnetic pole 5, after the recording gap layer 3 and pedestal 1 aredefined by ion milling and the pedestal 1 is notched to have the samewidth as that of the upper magnetic pole 5, is 4.0 μm to 4.3 μm.

When the method of manufacturing the merged MR head described above isemployed, a merged MR head satisfying all the following conditions canbe provided:

(1) the width 5w of the upper magnetic pole 5 is equal to or smallerthan 2 μm and the thickness of the upper magnetic pole 5 is equal to orlarger than 4.0 μm;

(2) the recording gap layer thickness 3t falls within the range of 0.1μm to 0.4 μm;

(3) the sidewall 3s of the recording gap layer 3 and the sidewall 1s ofthe notched portion of the pedestal 1 are aligned within the same planewhere the sidewall 5s of the upper magnetic pole 5 is present; and

(4) the height of the sidewall 1s of the notched portion of the pedestal1 falls within the range of 0.5 to 4 times the recording gap layerthickness 3t of the recording gap layer 3 having the same width as thewidth 5w of the upper magnetic pole 5.

In particular, a merged MR head satisfying all the following preferableconditions can be provided:

(1) the width 5w of the upper magnetic pole 5 is equal to or smallerthan 2 μm and the thickness of the upper magnetic pole 5 is equal to orlarger than 4.0 μm;

(2) the recording gap layer thickness 3t falls within the range of 0.3μm to 0.4 μm;

(3) the sidewall 3s of the recording gap layer 3 and the sidewall 1s ofthe notched portion of the pedestal 1 are aligned within the same planewhere the sidewall 5s of the upper magnetic pole 5 is present; and

(4) the height 8 of the notched portion, which is formed by notching thesidewall 1s of the notched portion of the pedestal 1 to have the samewidth as the width 5w of the upper magnetic pole 5, is 0.6 μm to 0.8 μmor is larger than 0.8 μm.

FIGS. 2A to 2E show a method of manufacturing a merged MR head accordingto the second embodiment of the present invention. In FIGS. 2A to 2E,portions that are identical to those of FIGS. 1A to 1F are denoted bythe same reference numerals as in FIGS. 1A to 1F, and a descriptionthereof will be omitted.

As shown in FIGS. 2C to 2E, the upper magnetic pole of this embodimentis formed by stacking two members, i.e., upper magnetic poles 5a and 5b.The upper magnetic pole 5b on the recording gap layer 3 side is made of,e.g., a material having a higher saturation magnetic flux density thanthat of a nickel-iron alloy. More specifically, a cobalt-nickel-ironalloy, a cobalt-tantalum-zirconium alloy, a cobalt-niobium-zirconiumalloy, iron nitride, or an iron-aluminum-silicon alloy is used.

In this embodiment, after the recording gap layer 3 is formed on apedestal 1 for an upper shield 2 in FIGS. 2A and 2B, the two uppermagnetic poles 5b and 5a are sequentially stacked on the recording gaplayer 3 in the pedestal 1 region by using a predetermined material.FIGS. 2D and 2E show steps identical to those shown in FIGS. 1E and 1D,and a detailed description thereof will thus be omitted.

FIGS. 3A to 3E show a method of manufacturing a merged MR head accordingto the third embodiment of the present invention.

The upper magnetic pole of this embodiment is constituted by twomembers, i.e., upper magnetic poles 5a and 5b, in the same manner as inthe second embodiment. The upper magnetic pole 5b on the recording gaplayer 3 side is made of, e.g., a material having a higher saturationmagnetic flux density than that of a nickel-iron alloy. Morespecifically, a cobalt-nickel-iron alloy, a cobalt-tantalum-zirconiumalloy, a cobalt-niobium-zirconium alloy, iron nitride, or aniron-aluminum-silicon alloy is used.

In this embodiment, furthermore, a pedestal 1a is made of a materialhaving a higher saturation magnetic flux density than that of anickel-iron alloy, in the manner as the upper magnetic pole 5b. Forexample, a cobalt-nickel-iron alloy, a cobalt-tantalum-zirconium alloy,a cobalt-niobium-zirconium alloy, iron nitride, or aniron-aluminum-silicon alloy is used.

According to this embodiment, in FIG. 3A, the pedestal 1a is formed onan upper shield 2 by using a specific material. FIGS. 3B to 3E showsteps identical to those of FIGS. 2B to 2E, and a detailed descriptionthereof will thus be omitted.

FIGS. 4A and 4B show a merged MR head according to the fourth embodimentof the present invention.

FIG. 4A shows the shape of the air bearing surface of the merged MR headmanufactured in accordance with the same manufacturing method as inFIG. 1. A notched portion height 8 of a pedestal 1 which is notched tohave the same width as that of an upper magnetic pole 5 is differentfrom a height 11 of the pedestal 1. Thus, the initial width of thepedestal 1 and the width of the pedestal 1 which is notched to have thesame width as that of the upper magnetic pole 5 are different from eachother, thus forming a corner 12. Due to the shadow of the upper magneticpole of an upper shield 2 which is formed when forming the pedestal 1 byion milling, a tapered portion 13 is formed.

In this embodiment, the time required for ion milling, which ispracticed by using the upper magnetic pole 5 in the steps of FIGS. 1Dand 1E as the mask, is set long within such a range that the thicknessof the upper magnetic pole 5 does not become smaller than a desiredthickness. When the ion milling time is adjusted in this manner, anotched portion height 9 of the pedestal 1 which is formed to have thesame width of the upper magnetic pole 5 is set close to the height 11 ofthe pedestal 1. As a result, a shape can be obtained in which the corner12 as shown in FIG. 4A is not formed in the tapered portion 13 formeddue to the shadow of the upper magnetic pole 5 of the upper shield 2which is formed when forming the pedestal 1 by ion milling.

As has been described above, according to the present invention, beforeforming a recording gap layer, a pedestal having a width slightly largerthan that of an upper magnetic pole and a height equal to or larger thanthe thickness of the recording gap layer is formed. The thickness of therecording gap layer at the pedestal corner can be set thin to 1/5 to 1/6the thickness of the recording gap layer on the pedestal, and the cornerof the recording gap layer can be exposed laterally at the lower portionof the sidewall of the upper magnetic pole.

More specifically, the milling time, which is required for defining therecording gap layer so as to have the same width as that of the uppermagnetic pole and a sidewall formed within the same plane where thesidewall of the upper magnetic pole is located by using the uppermagnetic pole as the mask, is decreased to 1/5 to 1/6 the conventionallyrequired time, and the amount of decrease in thickness of the uppermagnetic pole which is obtained at this time is decreased to 1/5 to 1/6the conventional amount. As a result, the amount of decrease inthickness of the upper magnetic pole, which is obtained when forming therecording gap layer and the pedestal by ion milling such that they havethe same width as that of the upper magnetic pole and that their sidesurfaces are aligned within the same plane by using the upper magneticpole as the mask, can be greatly decreased.

Since the upper magnetic pole can be formed thin in advance, thethickness of the photoresist used when forming the upper magnetic poleby electroplating using photoresist frame can be decreased, andvariations in width of the upper magnetic pole can be decreasedaccordingly.

What is claimed is:
 1. A method of manufacturing a merged MR head formedby sequentially stacking a lower shield, a lower shield gap, amagnetoresistive (MR) element, an upper shield gap, a lower magneticpole/upper shield, a recording gap layer, a coil, a coil insulatinglayer, and an upper magnetic pole on a side surface of a trailing edgeof a floating slider having an air bearing surface, the methodcomprising the steps of:forming a pedestal on a portion of said lowermagnetic pole/upper shield that includes said air bearing surface;forming said recording gap layer on said lower magnetic pole/uppershield and said pedestal; forming said upper magnetic pole, having awidth smaller than that of said pedestal by 0.1 μm to 2.0 μm, on saidrecording gap layer on said pedestal; and wherein said pedestal has aheight not less than twice a thickness of said recording gap layer todecrease widening of the fringe magnetic field during recording etchingand notching said recording gap layer and said pedestal by using saidupper magnetic pole as a mask, thereby forming a sidewall of saidpedestal to be on the same plane where a sidewall of said upper magneticpole is present.
 2. A method according to claim 1, wherein the etchingstep comprises the step of etching said recording gap layer and saidpedestal by ion milling.
 3. The method of claim 1, wherein the width ofsaid upper magnetic pole is not more than 2.0 μm.
 4. The method of claim3, wherein said upper magnetic pole has a thickness not less than 4.0μm,said recording gap layer has a thickness of 0.1 μm to 0.4 μm, and thenotch of said pedestal has a depth of 0.2 μm to 1.2 μm.
 5. The method ofclaim 1, wherein the notch has a depth not less than twice a thicknessof said recording gap layer.
 6. The method of claim 1, wherein saidupper magnetic pole includes first and second stacked divisionalmagnetic poles, said first divisional magnetic pole on a recording gaplayer side being made of a high-saturation magnetization material havinga saturation flux density higher than that of said second divisionalmagnetic pole.
 7. The method of claim 1, wherein said pedestal is madeof a high-saturation magnetization material having a saturation magneticflux density higher than that of a major material of said lower magneticpole/upper shield.
 8. The method of claim 1, wherein a high-saturationmagnetization material having a saturated magnetic flux density higherthan that of a major material of said lower magnetic pole/upper shieldis stacked on said pedestal on a recording gap layer side.